U.S. Officials Are Investigating North Korea in Sony Movie Hack

North Korean leader Kim Jong Un (C) gives field guidance during his visit to the Korean April 26 Cartoon Film Studio in this undated photo released by North Korea's Korean Central News Agency on Pyongyang Nov. 27.KCNA / Reuters

Several U.S. law enforcement agencies are investigating whether North Korea is behind the recent hacking of Sony Pictures' online networks and the illegal dissemination of at least five of the company's films, a senior U.S. official confirmed to NBC News.

There has been speculation that the cyberattack could be linked to an upcoming Sony Pictures film called "The Interview," a comedy that features a CIA plot to assassinate North Korean leader Kim Jong-un.

The comedy starring Seth Rogen and James Franco is scheduled for release December 25. A North Korean official blasted the film as a symbol of the "desperation" of American society in an interview with British newspaper The Telegraph.

Classified briefings to several U.S. agencies name North Korea among possible suspected perpetrators.

Attackers using the name Guardians of Peace, or G.O.P., have claimed responsibility for the hack of Sony Pictures' internal network. The attack began November 24, when employees' computers were reportedly plastered with messages bearing the phrase "Hacked by #GOP."

It's unclear how widespread the attack is, but emails to multiple Sony employees last week could not be delivered.

Digital copies of unreleased Sony films "Annie," "Mr. Turner," "Still Alice" and "To Write Love on Her Arms" -- as well as the war movie "Fury," which is currently playing in theaters -- appeared online November 27. Later that day, a person claiming to be "the boss of G.O.P." emailed reporters with links to purported stolen internal data.